1. Field
A paper feed mechanism is provided.
2. Related Art
FIG. 11 is a view schematically showing a generally employed paper feed mechanism 40 disclosed in Patent Application Publication No. H10-119374, which includes a metal cylindrical paper feed roller 41 on which protrusive portions 43 each having a predetermined width are formed at predetermined intervals. The protrusive portion 43 includes a plurality of projections 42 each having a predetermined height, a predetermined pitch, and an acute-angled top end on an outer peripheral surface of the paper feed roller 41 in the longitudinal direction.
Press contact rollers 45 are disposed opposite to the protrusive portions 43 such that a sheet of recording paper 44 is in tight contact with the paper feed roller 41 at a predetermined contact pressure.
As the press contact rollers 45 press the recording paper 44, the projections 42 of the protrusive portions 43 are pushed into the back surface of the recording paper 44. In this state, the paper feed roller 41 is driven to rotate such that the recording paper 44 formed as a board is fed while printing.
Referring to FIG. 12, a printer 46 equipped with the paper feed mechanism 40 further includes a platen roller 47 to the right of the paper feed roller 41. A thermal head 48 is allowed to be in contact with (head-down) or released from (head-up) the platen roller 47.
For the purpose of printing the color image on the recording paper 44 as the board such as a photographic printing paper, the generally employed paper feed mechanism 40 is operated to feed the recording paper 44 from the upstream side at the right side of the drawing to be interposed between the paper feed roller 41 that rotates in the direction of an arrow A and the press contact rollers 45 while holding the thermal head 48 in the head-up state. Different ink colors are printed on the recording paper 44 by performing the head-down and head-up operations of the thermal head 48 repeatedly as well as feeding the recording paper 44 back and forth in directions of A and B repeatedly such that a desired color image is printed.
The head-down operation of the thermal head 48 is performed at a starting position where a top edge 44a of the recording paper 44 is gripped between the paper feed roller 41 and the press contact roller 45 so as to start printing.
With the aforementioned structure, the printing cannot be performed in the area of the recording paper 44 from the top edge 44a to at least the distance of C. The resultant margin may waste the recording paper 44, thus leading to the cost increase.